Rates of women who are opting for preventive mastectomies, such as Angeline Jolie, have increased by an estimated 50 percent in recent years, experts say. But many doctors are puzzled because the operation doesn't carry a 100 percent guarantee, it's major surgery -- and women have other options, from a once-a-day pill to careful monitoring.

About 33 percent of adult men and 35 percent of U.S. women were obese in 2005-2006, according to a comprehensive survey by the federal government that includes physical examinations.

That’s more than 72 million people, according to the U.S. Centers for Disease Control and Prevention.

The new rates were slightly higher than the 31 percent and 33 percent reported in the 2003-2004 survey, the CDC said in a report released Wednesday. However, the increases were not considered statistically significant, health officials said.

The adult obesity rate has generally been climbing since 1980, when it was 15 percent. There have been occasional plateaus, as occurred between 1999-2000 and 2001-2002.

In the new report, obesity was most common in adults aged 40 to 59.

There were large differences by race for women — the female obesity rates in the 40 to 59 age group were 39 percent in white women, 51 percent in Mexican-American women and 51 percent in black women.

However, there were no racial or ethnic disparities in the male obesity rates, the CDC said.

The report also found that about a third of obese adults had not been told by a doctor or health care provider that they were overweight, although women heard such an assessment more often than men.